Cancer is a major public health problem. Currently, classification of cancer is based on phenotypic markers. The identification of unique molecular markers of cancer has led to development of new molecular cancer therapies. Movement toward a molecular characterization of cancer would have important clinical benefits, including (1) detecting cancer earlier, (2) predicting risk of precancerous lesion progression, (3) detecting margins in the operating room in real time, (4) selecting molecular therapy rationally and (5) monitoring response to therapy in rear time at a molecular level. Imaging the molecular features of cancer requires molecular-specific contrast agents which can safely be used in vivo as well as cost-effective imaging systems to rapidly and non-invasively image the uptake, distribution and binding of these agents in vivo. Radiographic imaging modalities such as CT and MRI, although useful for delineating the deep extent of advanced carcinomas, are not sufficiently sensitive to detect small, intraepithelial lesions. Optical imaging is a new modality which enables real time, high resolution imaging of epithelial tissue. Optical imaging systems are inexpensive, robust and portable. Optical imaging systems are ideally suited for early detection of intraepithelial disease and to assess tumor margins and response to therapy. The goal of this proposal is to integrate development of optical imaging systems and contrast agents with advances in functional genomics. We will develop molecular-specific, optically active contrast agents that can be applied topically. We will also develop inexpensive, rugged and portable imaging systems to monitor the three-dimensional profile of targeted biomarkers. These contrast agents and imaging systems will have broad applicability to many types of cancer; here, we will develop and test agents and imaging systems for the cervix, oral cavity and the lung, which represent more than 20% of both tumor incidence and mortality worldwide. We will test the safety and efficacy of these contrast agents and imaging systems in animal models, providing data to support phase I and II clinical trials. The aims of this proposal are to: (1) Develop optically active contrast agents to target four molecular signatures of neoplasia, including EGFR, MMP, telomerase and alpha v integrin; (2) to identify promising new biomarkers for which contrast agents will be developed using SAGE libraries, and to identify promising molecular probes for novel contrast agents using combinatorial methods; (3) to develop inexpensive, portable optical systems to image the morphologic and molecular signatures of neoplasia noninvasively in real time; and (4) to test these agents, delivery formulations and imaging systems in living biological systems of progressively increasing complexity. (5) Our final aim is to integrate these studies to develop a miniature imaging system, which when coupled with the contrast agents developed here, can be used for real time, molecular detection of neoplasia and to monitor, at the molecular level, whether a lesion is responding to therapy.